1. Field of the Invention
The invention relates to the utilization of a decommissioned power station chimney or industrial chimney made of concrete as a tower for a wind converter with high electrical output having with a rotor with a horizontal rotor axis upon whose point there are mounted flying rotor vanes.
2. Description of the Prior Art
Wind energy systems belong to a group of alternative, environmentally friendly renewable energy sources and are used to an increasing extent for the generation of electrical power. Wind is not available permanently as an energy source, nor at a uniform intensity. It is known that for these reasons wind power plants are usually erected in areas which have frequent and notably high wind velocities.
As a rule, most prior art wind energy systems include a tower comprising a concrete or steel construction or a mixed construction, including the associated foundation and, on the upper end of the tower, a wind converter with a rotary arrangement for free rotation through 360.degree. (Wind Power Systems, Springer Verlag, Berlin, DE 1988, pages 388, 390). With the aid of the rotary device, the converter is rotated concentrically into the respective wind direction in an automatic manner via corresponding measuring and control devices.
The operating heights of conventional converters are restricted to a hub height or rotor axis of 20 to 65 m by the high costs for foundations and tower and by problems in transporting completed towers or sections to the site. The highest nominal output yet known of a single converter was achieved in Germany with the wind power system GROWIAN and other prototypes, at about 1500 kW. These and other constructions however involved the disadvantage of a restricted tower height or of excessively high investment for higher towers, so that, in less windy inland regions, the chances for an economically viable power system are poor.
Basic research into utilization of wind energy by windmills was published in a re-print from 1926 in Betz, Wind-Energie, Okobuchverlag, Stauffen, DE, 1982 with illustrations of: frequency distribution of predominating wind velocities, illustration 1; distribution of the annual energy yield, illustration 34; alteration in wind velocity in dependence on measured height, illustration 2; and theoretical calculations for possible power outputs for wind power systems, shown for wind wheel diameters up to 100 m in a nomogram, illustration 10.
This basic document indicates that only those rotors with profiled vanes and horizontal axle position are favourable in energy terms, which use lift on the rotor as a parameter.
Wind wheels with a perpendicular axis are indicated for large-scale systems above 1000 kW, yet are shown as unfavourable from the energy point of view.
A prior art wind generating system is known from DE 31 06 777 A1, in which high towers, such as a chimney of a constructive height of 150 m and a diameter of 15 m are disclosed, about which wind wheels are to rotate in a vertical axis In a similar way, in WO 92/08893 discloses the use of an industrial chimney or tower which is still in operation. In this case two plates are mounted on support arms of a support ring at the chimney head or the chimney shaft which, due to their wind resistance, rotate about the operating chimney.
The theoretical principle that windmills rotating about a vertical axis have a very poor degree of efficiency and are inferior to rotors having a horizontal axis and different vane profiles, as established by the author Betz, applies for these prior art devices in references DE 31 06 777 al and WO 92/08893.
There is no indication to be found in these documents as to whether the chimney constructions given as an alternative may be simply used.
The document DE-C 830 180 discloses another prior art device including a guyed tower on which converters, which are mounted on jibs on the tower, have a degree of freedom of rotation about the tower. As soon as high winds or storms are to be expected, the jibs are lowered with the converters. If necessary, the cables used for lowering the converter are also used as guy cables for the tower to prevent the storm from bending the mast or to prevent the occurrence of dangerous resonant vibrations in the tower. The tower is clearly a system consisting of steel components with spread support feet.
Another prior art device known from DE-C 742 242 includes a lattice tower with structures freely rotatable about said lattice tower and upon which a plurality of identical converters of the same output are located. The system is extremely expensive to construct, both as regards the type of tower and as regards the support structures for low-power converters.
Further literary sources on this theme are given in the following. Their content is regarded as prior art and incorporated by reference into the disclosure of the present invention:
Bundeswirtschaftsministerium, Erneuerbare Energien verstarkt nutzen, Bonn, DE, May 95, 3rd edition [Federal Ministry of Economics, the increased use of renewable energy].
Company documents:
ENERCON, Aurich,DE,No 26605
Tacke, Windtechnik [Wind Technology], Salzbergen,DE,No 48499
Micon, Randers-Denmark, No 8900
German periodical: Sonnenenergie & Warmetechnik [Solar Energy and Heating Technology]1/96, pp 22-27 and 5
Rauser, Steigerung der Leistungsausbeute von Windenergie-Konvertern [Increase in the Output of Wind Energy Converter], Herrengut, Baden-Baden, DE, 1983.
ISET document sequence, Kassel 95 NMEP on width test 250 MW wind, Annual Evaluation 1994.
Windmessungen in gro.beta.er Hohhe [wind measurements at great height], Institut fur Meteorologie und Klimatologie and der Univesitat Hannover, DE, 1996.
Reports of the German Weather Service, privately published, Offenbach, DE 1983 and further years (up to 89)
Bundesforschungsministerium Forschungsbericht [Federal Research Ministry, Research Report ]T 85-146, measurements of wind field at various heights . . . and Report by G. Tetzlaff, Wind Measurement at Great Height, Eggenstein and Leopoldshafen, DE, 1986.
Muller, Fritz, Dynamische Berechnung von Massivschornsteinen [Dynamic Measurement of Solid Chimneys], Hauptverband Deutsche Bauindustrie, 1977.
Fordergesellschaft Windenergie e. v.,[Sponsoring Body for wind Energy (registered association)], Wind-power catalogue Vulkan-Verlag, Essen, DE, 1989.